Tired? Forgetful? Tingling hands and feet? It could be Vitamin B12 deficiency!

If you’re tired, forgetful, or having tingling of your hands and feet, it could be due to a low vitamin B12 level. In fact, the most common symptom of Vitamin B12 deficiency is tingling in feet and hands.

The reason it is important not to miss vitamin B12 deficiency is because it can cause permanent neuologic damage and yet early diagnosis and treatment can prevent all the neurologic damage if treament is given early enough. And treatment (monthly shots of B12 or a special B12 pill orally every day) is incredibly safe and effective. The amount of vitamin B12 in regular multivitamins is not enough to treat vitamin B12 deficiency.

If there is a possibility of low B12, you should get a serum Vitamin B12 level because prolonged B12 deficiency can cause permanent neurologic damage. And Vitamin B12 deficiency is common with an estimated 3.2% of persons over the age of 50 years being deficient.

In elderly patients, increased irritability and increased fatigue can be due to B12 deficiency. Every patient with dementia should be checked to see if Vitamin B12 deficiency is the cause (altho it is a rare cause of dementia, perhaps only one out of 100 cases of dementia). Everyone who is concerned about forgetfulness should get a Vitamin B12 blood test.

Symptoms of Parkinson’s disease and other neurologic diseases can (occasionally) be caused by Vitamin B12 deficiency or made worse (more commonly) by vitamin B12 deficiency.

The National Health and Nutrition Survey defines biochemical vitamin B12 deficiency as 1) a serum B12 level of less than or equal to 200 picograms per ml and a methylmalonic acid (MMA) of greater or equal to 270 nanomoles per liter or 2) a serum B12 level of greater than 200 picograms per ml and a methylmalonic acid (MMA) of greater or equal to 270 nanomoles per liter.

The laboratory evaluation for possible B12 deficiency is a complete blood count and a serum vitamin B12 level. If the B12 level is below normal or in the low normal range a methylmalonic acid level should be drawn. The methylmalonic acid level in the blood is above normal in vitamin B12 deficiency. The big problem with the methylmalonic acid level is that it can be very expensive, perhaps $200.

Vitamin B12 deficiency is treated with once a week IM shots of 1000 micrograms of B12 for four weeks and then monthly for life. Oral treatment with 1000 micrograms daily for life is also effective.

The big thing is to test for B12 deficiency if you have a symptom it might be due to. Vitamin B12 deficiency is one of the most easily treatable diseases there is. And one of the first things medical students learn is—don’t miss the most treatable disease that could be causing the patient’s symptoms.